Electromagnetic oscillation motor

ABSTRACT

An electromagnetic oscillation motor has an asymmetrical four-pole stator with an a.c. winding including two paths connected in parallel. Each path includes two serially connected coils received on the adjacent poles of the stator. The poles of the stator forming one pair are offset in opposite directions away from each other, while the poles forming the other pair are offset toward each other relative to the symmetry axes of their corresponding poles of the armature, through a distance equalling one half of the angular width of the stator winding. The oscillation motor further comprises a four-pole symmetrical armature, its poles being provided with a d.c. winding. The coils of this winding are connected in pairs in the matched-series fashion, while the pairs themselves are interconnected in opposition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to special-purpose electric motors used fordriving various work-performing members through angular oscillations,and more particularly it relates to electromagnetic oscillation motors.

2. Description of the Prior Art

There is known an electromagnetic oscillation motor (see SU Inventor'sCertificate No. 1,040,573; Int. Cl.³ HO2K 33/14, dated 1983) having astator with a winding received on two pairs of poles symmetricallyarranged in a circle, the parallel paths of this winding being connectedto a voltage source through respective rectifiers connected inopposition to each other, and a salient asymmetrically armature whosepoles are offset in pairs in opposite directions relative to thesymmetry axis by one half of their angular width.

In this known motor, the incorporation of the rectifiers has been foundto affect the power characteristics of the motor, while the asymmetry ofits armature, the small spacing of the adjacent poles in particular, hasbeen found to incur manufacturing difficulties in application of thebias winding onto the armature, and to impair the cooling conditions.Furthermore, in motors of higher power ratings the asymmetry of thearmature adversely affects the dynamic characteristics of the motor.

There is also known an electromagnetic oscillation motor (see FR Pat.No. 1,552,754; Int. Cl. HO2K, published on Jan. 1, 1969) comprising afour-pole symmetrical armature and an asymmetrical four-pole statorwhose poles are offset in the same direction through one half of theangular width of the poles. The a.c. winding of the stator includes twopaths connected in parallel and received on the opposite poles of thestator. Each path has two serially connected coils and is connected to apower supply source through a semiconductor diode. During oddhalf-cycles, the alternating current of the power supply source isdirected through one parallel path of the stator winding, and duringeven half-cycles it is directed through another path. Consequently,corresponding magnetic fluxes are excited by the two paths of themagnetic circuit, generating sign-variable driving torque resulting inoscillations of the armature in accordance with the harmonic law.

However, the incorporation of the half-wave rectifiers in this knownstructure of an electromagnetic oscillation motor impairs its powercharacteristics and distorts the current curve, thus adversely affectingthe power supply source. Moreover, this structure prohibits fullcompensation for the electromotive force of self-induction by using biascircuits, on account of the parallel paths of the stator winding beingarranged on the opposite poles, which involves intersection of themagnetic fluxes developing the driving effort. The extended length ofthe magnetic circuit further impairs the power characteristics of theoscillator motor.

SUMMARY OF THE INVENTION

It is an object of the present invention to create an electromagneticoscillation motor wherein the structural design of the stator and thearrangement of the winding coils should enhance the efficiency factorand the power factor, and should also provide for controlling theamplitude of oscillations of the armature by varying the bias current.

This is achieved in that an electromagnetic oscillation motor comprisinga symmetrical four-pole armature with a d.c. winding and an asymmetricalfour-pole stator with an a.c. winding made of two paths connected inparallel, each path including two serially connected coils. Inaccordance with the present invention, the adjacent poles of the stator,forming one pair, are offset in opposite directions away from eachother, while the adjacent poles forming the other pair are offset towardeach other relative to the respective symmetry axes of theircorresponding poles of the armature through an extent corresponding toone half of the angular width of the poles of the stator, eachrespective path of the a.c. winding being received on its correspondingpair of the adjacent poles of the stator, and the d.c. winding coils ofthe armature being connected in pairs in matched series and received onthe adjacent poles of the armature, these pairs of coils being connectedin opposition.

The invention provides for enhancing the reliability of anelectromagnetic oscillation motor and for bringing down itsmanufacturing cost.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be further described in connection with appendeddrawings illustrating an embodiment of the present invention, wherein:

FIG. 1 schematically illustrates an electromagnetic oscillation motorconstructed in accordance with the invention; and

FIGS. 2a and 2b present the curves of variation in time of magneticfluxes crossing the annular air gap of the electromagnetic oscillationmotor embodying the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

In the drawings, the electromagnetic oscillation motor has a baseplate 1(FIG. 1) supporting on feet 2 a salient-pole stator which isasymmetrical circularly and mirror-symmetrical with respect to thesymmetry axis A-A', the stator having poles 3, 4, 5 and 6 supportingthereon a d.c. winding connected to an a.c. power supply source 7. Theadjacent poles 3 and 4 of the stator, forming one pair, are offset inopposite directions from one another with respect to the axes ofsymmetry of the respective poles 8 and 9 of the armature of the motorthrough a distance b/2 equally one half of the angular width "b" of thestator poles 3 and 4. The adjacent poles 5 and 6 of the stator, formingthe other pair, are offset toward each other relative to the axes ofsymmetry of their corresponding poles 10 and 11 of the armature likewisethrought the distance b/2.

The a.c. winding includes two paths connected in parallel. One path is aseries connection of two coils 12 and 13 received on the poles 3 and 4which are spaced in excess of the mean inter-pole spacing π equalling##EQU1## where R is the radius of the bore in the stator. The other pathis a series connection of two coils 14 and 15 received on the slatorpoles 5 and 6 which are spaced, as it has bean already explained, by adistance short of the mean inter-pole spacing π.

Mounted inside the stator on a rotatable shaft 16 with the aid of a key17 is a symmetrical four-pole armature with its d.c. winding. The coils18 and 19, 20 and 21 of the d.c. winding are connected in pairs inmatched series and received, respectively, on the adjacent poles 9, 10and 8, 11, the pairs being interconnected in opposition to each other.The stator and armature are mechanically interconnected with the aid ofantifriction bearings (not shown in the drawing), and also throughresilient elements 23 operatively connected with an arm 24 fast on theshaft 16. Depending on the required amplitude of oscillations, awork-performing member may be secured either on the shaft 16 of theoscillation motor or on the arm 24.

The following symbols are used in the drawing. FIG. 1: the totalmagnetic flux φ in the paths B and C of the magnetic circuit; N andS--the respective polarities of the poles 3, 4, 5, 6 of the stator andof the poles 8, 9, 10 and 11 of the armature.

FIG. 2 illustrates the time curves of variation of the magnetic fluxesφ, 100 .sub.˜, φ₋ in the annular air gap of the oscillation motor, whereφ.sub.˜ is the magnetic flux developed by the winding of the stator, φ₋is the magnetic flux developed by the winding of the armature, φ is thetotal magnetic flux, t is time, and ω is the conditional rotationalspeed of the magnetic flux.

The herein disclosed electromagnetic oscillation motor operates, asfollows.

In the situation shown in FIG. 2a, during the half-cycle from 0 to π ofthe alternating current flowing through the stator winding, thealternating magnetic flux φ.sub.˜ in the path B (FIG. 1) of the magneticcircuit is added to the permanent magnetic flux φ₋ (FIG. 2a) developedby the d.c. winding of the armature, the resultant magnetic flux φ beingconditionally positive. With the total magnetic flux φ in the path B(FIG. 1) of the magnetic circuit being at its maximum, the flux φ (FIG.2b) in the path C (FIG. 1) practically equals zero. During thesuccessive half-cycle from π to 2π of the alternating current flowingthrough the stator winding the process is reversed: the total flux φ(FIG. 2b) in the path C (FIG. 1) is at the maximum, whereas the flux inthe path B practically equals zero. Consequently, there is created asign-variable driving torque causing angular oscillations of thearmature according to the harmonic law, one of the preconditions of thedevelopment of this driving effort in the operation of the oscillationmotor being the asymmetrical arrangement of the poles 8, 9, 10 and 11 ofthe stator relative to the symmetry axes of the corresponding poles 8,9, 10 and 11 of the armature, with an angular shift through one half b/2of the angular width "b" of the pole 3, 4, 5 or 6.

The herein disclosed electromagnetic oscillation motor offers anenhanced efficiency factor, owing to the stator winding being directlyconnected to the source 7 of alternating current, and also to the factthat all the poles 3, 4, 5, 6 of the stator and all the poles 8, 9, 10and 11 of the armature take part all the time in the development of theelectromagnetic effort. The incorporation of the d.c. winding forbiasing the armature provides for compensating for the reactive power,and thus for stepping up the power factor (cos ψ).

By controlling the bias current of the armature, it is possible to varythe amplitude of the angular oscillations. With the coils 18 and 19, 20and 21 of the armature winding being connected in pairs, counting fromthe power source 22, in a matched-series fashion, and with the pairsbeing interconnected in opposition, the electromotive force developed atthe terminals of the armature winding equals zero.

With no semiconductor rectifiers included in its structure, themanufacturing cost of the herein disclosed oscillation motor is muchlower, whereas its reliability characteristics are much batter.

The invention can be employed in various devices where thework-performing member is driven through repeated angular reciprocationsor oscillations, widely used in various trades and industries, e.g. ingeneral engineering for oscillation grinding, in agriculture foractuating oscillating screens and oscillating conveyers, in artificialblood circulation systems in medicine.

We claim:
 1. An electromagnetic oscillation motor comprising asymmetrical four-pole armature with a DC winding and an asymmetricalfour-pole stator with an AC winding made up of two parallel-connectedpaths, each said path including two series-connected coils (12, 13 and14, 15), characterized in that the adjacent stator poles (3, 4) formingone pair are offset in opposite directions, while adjacent poles (5, 6)forming another pair are offset toward each other with respect to theaxes of symmetry of respective poles (8, 9 and 10, 11) of the armatureto a distance (b/2) equal to one half of the width (b) of stator poles,each path of the AC winding being received on the respective pair ofadjacent stator poles (3, 4 and 4, 6), and, the coils (18, 19 and 20,21) of the DC winding are connected in pairs in a matched-series fashionand received on the adjacent poles (9, 10 and 8, 10) of the armature,the pairs of coils (18, 19 and 20, 21) being connected in opposition.